1. Field of the Invention
The present invention relates to an inclination detector for detecting that an inclination angle exceeds a preset value. The present invention is applied to a vehicle overturn detection device for detecting a transition state to overturn of the vehicle by detecting an inclination angle of the vehicle. The vehicle overturn detection device is used to determine an activation timing of a safety device for protecting passengers when the vehicle overturns.
2. Related Art
As shown in FIG. 6, a conventional inclination detector 200 has a cylinder-shaped mass 203 and a cylinder-shaped magnet 202 disposed inside the mass 203. The magnet 202 and the mass 203 are elastically biased by a spring 204 upwardly. As a result, the initial position of the magnet 202 and the mass 203 is determined by balance of the biasing force of the spring 204 and the gravitational force acting to the magnet 202 and the mass 203. A pole-shaped lead switch 201 is inserted into a hole 202a of the magnet 202 as an axis. The inclination detector 200 is attached to the vehicle in such a manner that the axis-direction of the inclination detector 200 substantially corresponds to the vertical direction of the vehicle. When the vehicle inclines, the biasing force caused by the spring 204 becomes larger than component force toward the spring 204 of the gravitational force acting to the magnet 202 and the mass 203. As a result, the magnet 202 and the mass 203 move toward the lead switch 201. When the inclination angle of the vehicle reaches a preset value, the magnet 202 and the mass 203 move to a preset position where contacts of the lead switch 201 are closed; thereby detecting the overturn transition state of the vehicle.
However, the above-mentioned inclination detector 200 can not detect a direction of inclination. Therefore, when the inclination detector 200 is used to detect the overturn transition state of the vehicle, the detector 200 can not discriminate whether the vehicle is going to overturn on the right side or the left side with respect to a running direction of the vehicle. Further, the magnet 202 and the mass 203 may move due to vibration or shock generated during driving of the vehicle, resulting in an instability of a detection signal.